How Electricity Gets to You

Understanding Electricity Demand and Supply

The Nature of Electric Grids

• Electric grids are vast machines that deliver electricity from various energy sources, such as water, gas, or wind, often from great distances.

• Unlike water systems that can store extra supply, electric grids operate with zero slack; demand must be met instantaneously.

Variability in Electricity Demand

• Converting natural fuels into electric power is complicated due to fluctuating demand throughout the day and year.

• Seasonal trends show January has high demand for heating while July peaks due to air conditioning usage during summer heat.

Daily Demand Patterns

• In January, electricity use spikes twice daily: around 7 AM when people wake up and again in the evening after work.

• In contrast, July sees peak usage later in the afternoon or early evening depending on regional climate conditions.

Special Events Impacting Demand

• Holidays and events like Super Bowl Sunday can drastically reduce electricity demand as people gather socially and turn off appliances.

Matching Supply with Demand

• Utilities must instantly match supply to whatever demand arises by layering different energy sources.

Energy Sources in Electricity Generation

Base-load Power Generation

• Nuclear power stations provide stable base-load electricity but cannot quickly adjust output due to long startup times.

• Coal plants also serve as a continuous source of power but similarly take time to reach operational temperatures.

Peaker Plants for Fluctuating Demand

• Natural gas-fired plants are crucial for meeting short-term spikes in demand because they can start up quickly compared to coal or nuclear plants.

Efficiency of Natural Gas Plants

• Simple cycle combustion turbines convert natural gas into electricity efficiently and can reach full power within 15 minutes.

The Role of Renewable Energy Sources

Integration of Renewables into the Grid

• The rise of renewable energy sources like solar and wind introduces variability; their generation is free once installed but depends on weather conditions.

Challenges with Renewable Energy

• A sunny day may lead to excess electricity production while cloudy days could necessitate reliance on peaker plants for additional power.

Electricity Storage and Grid Management

Challenges of Renewable Energy Integration

• The reliance on natural phenomena for renewable energy means that supply cannot match demand as effectively as traditional energy sources like nuclear, coal, and natural gas.

• Grids are being redesigned to allow for a mismatch between supply and demand, particularly minute-to-minute, with storage solutions being essential but challenging to implement.

Economic Viability of Battery Storage

• An average American household consumes about 30 kilowatt-hours daily; current lithium-ion battery costs make one-day's storage economically impractical at around $3,900 per household.

• Colorado has implemented four battery-electric storage systems on a minor scale, with the largest serving Fort Carson army base by charging during low-demand periods.

Long-Term Savings vs. Immediate Costs

• The Fort Carson system is expected to save approximately half a million dollars over its lifespan despite high initial costs; however, such investments are not practical for widespread grid application currently.

• Even if production capacity for batteries increased significantly, the long-term savings do not justify immediate investment for most consumers or utilities.

Electric Vehicles as Potential Storage Solutions

• With projections indicating that one-third of new car sales in the US will be electric by 2030, EV batteries could serve as a significant source of grid storage. A Rivian R1T can theoretically power an average household for four and a half days.

• The concept of vehicle-to-grid technology allows EV owners to charge their vehicles when electricity is cheap and return it to the grid during peak demand times while receiving compensation from utility companies.

Hydroelectric Power: A Reliable Alternative

• Hydroelectric power combines environmental benefits with reliability; it can quickly respond to demand changes similar to natural gas peaker plants while maintaining near-zero carbon impact.

• Facilities like Cabin Creek Generating Station utilize price arbitrage by pumping water during low-cost electricity periods and generating power when prices rise, helping stabilize wind and solar output fluctuations.

Transmission Challenges in Electricity Distribution

• Despite reductions in coal usage over the past decade, 42% of Colorado's electricity still comes from coal-fired plants concentrated at just six sites; efficient long-distance transmission remains crucial for modern grids.

• Long-distance transmission faces challenges due to energy loss through heat conversion; balancing centralized production economies with transmission efficiency is key in modern electrical infrastructure design.

What Makes High-Voltage Transmission Efficient?

Importance of Voltage in Electricity Transmission

• Higher voltage reduces electricity loss during transmission; doubling the voltage quarters power loss.

• The Craig Generating Station connects to high-voltage lines (345 kilovolts), resulting in only 3.2% electricity loss over a 75-mile stretch to Rifle, Colorado.

• Lines operating at 765 kilovolts can carry six times more electricity than 345 kV lines and experience as little as 0.6% loss per 100 miles.

Advantages of Direct Current (DC) Over Alternating Current (AC)

• DC transmission is even more efficient than high-voltage AC, with losses as low as 0.45% per 100 miles.

• Converting power to DC for long-distance transmission can be economically favorable despite higher initial conversion costs.

Case Study: Pacific DC Intertie

• The Pacific DC Intertie transmits cheap hydroelectric power from Oregon to Los Angeles during summer when demand is high.

• In winter, excess electricity from LA is sent back north to support heating needs in the Pacific Northwest.

Infrastructure Challenges in Local Distribution

• In populated areas near Interstate 70, using lower voltages like 230 kilovolts becomes necessary due to construction costs associated with higher voltages.

• A substation transforms electricity down from 345 kilovolts to lower voltages for local distribution, balancing efficiency and cost.

Final Steps in Power Distribution

• Smaller substations further reduce voltage levels down to usable levels (12.47 kilovolts or less), ensuring compatibility with residential and commercial buildings.

• This process illustrates the complexity of delivering electricity efficiently while managing infrastructure costs effectively.